Dry Firing
Here is why I try to never dry fire a revolver with a firing pin mounted in the hammer.
This is Colt second Generation hammer. Notice the shape of the firing pin. When the hammer falls and dents the primer of a live round of ammo, the primer cushions the blow slightly.
If the revolver is dryfired, the hammer slams to a violent stop against the frame. I have some background with products for the military regarding G forces and how much a product can stand before it breaks. The G forces exerted on the tip of the firing pin when the hammer slams to a stop are astronomical. Thousands of Gs. So if the tip of the firing pin is unsupported or not cushioned by a primer or a snap cap, the narrow tip wants to keep right on going. Yes, I have seen it happen. It is not guaranteed to snap the tip off a firing pin the first time, but do it enough and you may find the tip of the pin is missing. I have drawn a line across the firing pin where the separation is most likely to happen.
This is the firing pin on my remaining Uberti Cattleman. Almost identical in shape to the Colt firing pin. And just as likely to snap off.
One of the reasons Ruger Vaqueros can be dry fired without damage is the firing pin, besides being mounted to the frame, is shaped more like a hockey puck with the firing pin projecting off the surface. A shape like that is much less likely to be damaged by dry firing.
While I'm on the subject, here is a photo of a Smith and Wesson Model 14-3 hammer. Notice the shape of the firing pin.
And here is where it might be likely to break if dry fired too much. Another reason why I never dry fire revolvers with firing pins mounted in the hammer.
While I'm at it, some guys like to use spent cartridges as snap caps. Think about it for a minute. After a primer has been struck several times, the dent in it will be completely reshaped. It will no longer be supporting the firing pin when the hammer falls. There will be no cushioning or gentle deceleration for the tip of the firing pin, it will want to keep right on going.
If I am going to dry fire a revolver, I use actual snap caps which are designed for the purpose.
I never use spent rounds with dented primers.